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Researchers
at the National University of Singapore have invented a graphene-based
polarizer that can broaden the bandwidth of prevailing optical
fibre-based telecommunication systems.
The
graphene research team, led by Professor Kian Ping Loh at the National
University of Singapore, invented an ultra-slim broadband polarizer that
uses graphene, a single-atomic-layer crystallized carbon, to convert
light beam into polarized light. This is the first experimental
demonstration of using graphene as an ultrathin waveguide to couple and
modulate light. Light modulation by means of polarization management is
vital to avoid signal fading and error in coherent optical
communications as well as optical gyroscopes and interferometric
sensors.
In
principle, the polarizing ability of graphene covers the
telecommunication bands from visible to mid-infrared. This means that
graphene polarizer can provide all-in-one solution for multiple-channel
high-speed optical communications, the researchers said.
The
researchers skilfully transferred graphene grown by chemical vapor
deposition on the side-polished optical fibre to fabricate the graphene
polarizer and measured light polarization at different wavelengths.
Unlike polarizers made from thin metal film or semiconductor dielectric,
a graphene polarizer has the unique ability to filter out
transverse-magnetic-mode and supports transverse-electric-mode surface
wave propagation.
The broadband graphene polarizer work was published in the journal Nature Photonics and appeared online on 29 May 2011.
“The
results reported in this paper can have a strong impact in the
development of graphene-based optical devices for photonic
applications…the science behind it is excellent…” says professor Antonio
Castro Neto of National University of Singapore.
The
Singapore team has earlier pioneered graphene mode-locked lasers in
2009. This work was another breakthrough in bringing graphene photonics a
step closer to real applications.
“In
the near future, we can envision ultrathin graphene-based photonic
circuits with multiple functions of light creation, routing, modulation
or detection,” said Dr. Qiaoliang Bao, who is the project leader of the
pioneering work.
